Johnson is still recovering from seven hours of reconstructive surgery Monday after a weight bar fell on his neck, crushing his larynx and throat. The senior received a visit from the seventh-ranked Trojans' coaching staff, although his family is limiting his visitors.

"He's feeling good, he's functioning well and all that," USC coach Pete Carroll said. "He can't move very much because they want to keep his head and his neck very still. ... These are long, hard days for him, but he's like the commander of the Starship Enterprise with all the technology around him."

Johnson also opened a Twitter account to communicate with fans sending good wishes.

"Thank you every1 4 all the love and support," Johnson says in his first tweet.

USC (3-1, 1-1 Pac-10) also received encouraging news Wednesday about two top players heading into Saturday's showdown with No. 24 California (3-1, 0-1).

Quarterback Matt Barkley showed more improvement in his arm motion during practice. The freshman played through pain from a bruised right shoulder last weekend against Washington State after missing the Trojans' upset loss at Washington, but Barkley is much closer to full strength this week.

"Without question it was the best day for his arm motion," Carroll said. "It's still not 100 percent, but it was the best he's been."

USC also had freshman defensive end Nick Perry back in practice after the Pac-10's sacks leader missed Tuesday's workout with a bruised knee. Perry has six sacks in his first four games.

Receiver Ronald Johnson did some running on the side for the first time since breaking his collarbone in the Trojans' mock game one week before the season opener. Johnson, a projected starter this fall, has targeted USC's trip to Notre Dame on Oct. 17 for his return, although Carroll still is being cautious.

"I would bet RoJo is going to be pretty close in the next couple of weeks," Carroll said.